With the gradual rise of Web-2.0 based platforms, Internet users were given the possibility to interact with each other in virtual communities. Originating from this development was the concept of user-generated content (UGC), which implies that people were able to enrich each other’s user-experiences by sharing creative efforts and communicating openly (O’Reilly, 2007).   As Web 2.0 features continued to grow, marketers became aware of the opportunities this new development online created and how they could use it to their advantage (De Chernatony & Christodoulides, 2004). The development online however also faces companies with challenges, as consumers now are able to create and share opinions and thoughts about brands, which to an extent is uncontrollable by companies (Christodoulides et al., 2012). Just as marketer-controlled communication can create new brand associations in the minds of consumers, for better or worse - so can also externally-generated communication, such as brand-related UGC, do.   Knowing that consumers generally trust what other consumers say about products more than marketing communication (Cheong & Morrison, 2008; Song & Yoo, 2016), and that there does not exist much research on how consumers perceive brand-related UGC, this is a considerably important topic to study. A classic way of studying communication effectiveness is through credibility, which is argued to be a major determinant of whether consumers accept and adopt what is communicated (e.g. Hovland et al., 1953). Thus, the purpose of this thesis is to gain an understanding of how consumers assess credibility of brand-related UGC and furthermore, what their consequent responses are.   A qualitative approach was taken as the purpose is to gain insight rather than proving a point. The interviews were semi-structured and formed around three Instagram posts relating to a specific brand, which were deliberately chosen based on the content of the theoretical framework developed. Through using these example cases, interviewees’ first reactions could be captured and their reasoning around credibility could be followed and discussed.   The results from this study indicate that there exists a certain level of irritation as well as a scepticism towards brand-related UGC. This seem to stem from a suspicion that most content that promotes products and brands is part of sponsored collaborations, into which consumers put noticeably much distrust. Beyond questioning sponsorship, it was also found that the source played a particularly important role when assessing credibility. When a source is familiar, it is easier to determine credibility of brand-related UGC, and credibility furthermore increases with perceived expertise, attractiveness and trustworthiness. The channel through which a message is communicated also matters, as it is more difficult to be ingenuine through a video than an image or a text, which implicated that consumers may find videos more credible than other media formats. The message itself was also deemed to influence the credibility assessment, as the message was questioned both based upon common sense but also on knowledge and previous experience.   As for practical implications, this study indicates that encouraging or generating positive brand-related UGC through paid collaborations, is a balancing act, into which much consideration needs to be put. With the evident irritation that consumers feel when it comes to brand-related UGC, marketers should be careful to push too much positive brand communication onto the consumer, or it will turn negative. To come across as genuine, the “who”, ”what” and ”how” of communication should be carefully considered.